Hello!
It all depends on how much you fly. It could be less, it could be more and also if you have layovers it will increase your salary as you would be getting allowances on top of your salary. As they are also flying to Europe I would think that the allowances are pretty high because of the high costs.
I think you should go for the interview! They will explain everything in details for you. One good thing with Oman Air is as they are a small airline it's easier to get to know the other crew and gives you that family environment.